PULMONARY ANGIOGRAPHY USING 16 SLICE MULTIDETECTOR COMPUTED TOMOGRAPHY IN NORMAL DOGS

We report a canine computed tomography (CT) pulmonary angiography technique using multidetector CT (MDCT). CT pulmonary angiography using a 16 slice MDCT was performed on five healthy, anesthetized beagles. A helical acquisition with pitch of 1.4 was used. The time delay for the angiographic study was determined using a bolus‐tracking program. A dose of 400 mg I/kg of nonionic contrast medium (Iohexol 300 mg I/ml) was administered to each dog via a cephalic catheter using an angiographic power injector at a rate of 5 ml/s. In two dogs a second study, using a contrast medium dose of 200 and 600 mg I/kg was performed. Arterial enhancement of transverse and reformatted images was classified subjectively as excellent, good, or poor, and assessed objectively by measuring Hounsfield units at the right main pulmonary artery. Angiographic studies were evaluated by two radiologists to determine the number of subsegmental arterial branches visualized. The median number of subsegmental arterial branches identified was five (range: 2–7). Based on the time attenuation curve obtained by the bolus‐tracking program, there was consistent enhancement of the right main pulmonary artery beginning at 6 s and peaking at 8 s in 4/5 dogs. The contrast medium dose of 400 mg I/kg produced good to excellent vascular enhancement in the same 4/5 dogs. A dose of 200 mg I/kg resulted in poor enhancement. CT pulmonary angiography using MDCT and an automated bolus‐tracking program allows rapid, consistent evaluation of the pulmonary vasculature using a single dose of 400 mg I/kg of contrast medium.     

Effect of repeated administration of tirilazad mesylate on healthy and endotoxemic calves: a pilot study.

Tirilazad mesylate (TM:U74006F), a nonglucocorticoid 21-aminosteroid (lazaroid), is beneficial in the treatment of experimentally-induced ischemic injury following brain and spinal cord trauma, subarachnoid hemorrhage, hypovolemic shock and endotoxemia. This study investigated the effects of TM following repeated administration in sixteen healthy and endotoxemic calves. Group A calves received TM 3 mg/kg IV; group B calves received Escherichia coli endotoxin in increasing doses (0.1 to 20 micrograms/kg IV); group C calves received TM and endotoxin and group D calves received sterile saline (10 mL). Endotoxin, TM and saline were given every eight hours for five days. Mild, transient tachypnea was observed following TM administration. The drug suppressed clinical signs of endotoxemia until larger doses of endotoxin were given. At necropsy no substantial lesions were observed in groups A and D. Groups B and C had lesions consistent with endotoxemia but only group C calves had evidence of abomasal and ruminal ulceration. Although TM may be of benefit in the treatment of endotoxemia, further studies are needed to determine the optimal dosage and potential side effects in the endotoxic bovine neonate.     

Vaccination of calves against bovine herpesvirus-1: assessment of the protective value of eight vaccines

Eight separate, but related experiments, were carried out in which groups of six calves were vaccinated with one of eight commercial vaccines. In each experiment the vaccinated calves were subsequently exposed to three calves infected with virulent bovine herpesvirus-1 (BHV-1). In each experiment, all infected donor calves developed a typical severe infectious bovine rhinotracheitis (IBR) infection and excreted virus in their nasal secretions of up to 10(8.00) TCID50/0.1 ml. One live BHV-1 gE-negative vaccine (A) and three modified live vaccines (B, C, D), administered intranasally, all protected against clinical disease. The calves vaccinated with one vaccine (C) also did not excrete virus in the nasal secretions, whereas the calves protected by vaccines A, B and D excreted virus in their nasal secretions but at low titres (10(0.66)-10(1.24) TCID50/0.1 ml). A fourth modified live vaccine (E), given intramuscularly, failed to prevent mild clinical disease in the calves which also excreted virus in the nasal secretions at titre of 10(1.00) TCID50/0.1 ml. An analogous result was given by the calves vaccinated with either of the two inactivated vaccines (F and G) or with a BHV-1 subunit vaccine (H). All calves developed mild clinical signs and excreted virus at titres of 10(2.20)-10(3.12) TCID50/0.1 ml. Calves vaccinated with C vaccine were subsequently given dexamethasone, following which virus was recovered from their nasal secretions. The virus isolates did not cause disease when calves were infected and appeared to be closely related to the vaccine strain.     

A comparison between injection speed and iodine delivery rate in contrast-enhanced computed tomography (CT) for normal beagles

The purpose of this study was to compare between the injection speed and iodine delivery rate in order to establish a concept for reproducible contrast timing in contrast-enhanced computed tomography (CT) for small animals. Clinically healthy beagle dogs were administered a nonionic iodinate contrast medium at a dose of 800 mgI/kg; they were divided into 3 groups (n=5, crossover method): in one group, the injection speed was fixed at 1.0 ml/sec, and in the second and third groups, the iodine delivery rate was fixed (the injection durations were 30 and 60 sec, respectively). The variation in scatter of the time to aortic and hepatic peak enhancement in the fixed iodine delivery groups was lower than that in the fixed injection speed group. These results suggest that in contrast-enhanced CT for small animals, the contrast medium should be injected at a fixed iodine delivery rate in order to provide reproducible contrast timing.     

Malabsorption of vitamin A in preruminating calves infected with Cryptosporidium parvum.

Serum retinol, retinyl palmitate, and total vitamin A concentrations, and jejunoileal morphology were examined in neonatal calves infected with Cryptosporidium parvum. Group-1 calves served as noninfected controls and, after an adjustment period, were given 50 ml of saline solution i.v. every 12 hours for 6 days. Group-2 calves were inoculated with 10(7) C parvum oocysts and, after the onset of diarrhea, were given 50 ml of saline solution i.v. every 12 hours for 6 days. Group-3 calves were inoculated with 10(7) C parvum oocysts and, after the onset of diarrhea, were treated with difluoromethylornithine (DFMO, 200 mg/kg of body weight i.v., q 12 h) for 6 days. Group-4 calves were naturally infected with C parvum. Jejunoileal biopsy specimens were excised from calves of groups 1-3 at 3 and again at 15 to 16 days of age. During the course of diarrhea and 3 days after saline or DFMO administration, water-miscible retinyl palmitate was administered orally (2,750 micrograms/kg) to each calf in each group. Cryptosporidium parvum infection was associated with significant (P < or = 0.05) reduction in postadministration serum retinol, retinyl palmitate, and total vitamin A concentrations in calves of groups 2, 3, and 4. Cryptosporidium parvum infection caused significant (P < or = 0.05) reduction in villus height. Decreased villus height, villus blunting and fusion, and attenuation of the intestinal mucosa were associated with reduced absorption of vitamin A, as indicated by lower peak postadministration retinyl palmitate concentration in C parvum-infected calves. Intravenous administration of DFMO to group-3 calves did not improve retinol absorption.(ABSTRACT TRUNCATED AT 250 WORDS)     

EFFECT OF CONTRAST MEDIUM INJECTION DURATION ON PEAK ENHANCEMENT AND TIME TO PEAK ENHANCEMENT OF CANINE PULMONARY ARTERIES

Our goal was to investigate the effect of contrast medium injection duration on pulmonary artery peak enhancement and time to peak enhancement. Fourteen dogs were allocated into one of seven predefined weight categories, each category contained two dogs. Dogs in each weight category were assigned to group A or B. Animals in each group received a different contrast medium injection protocol. In group A, a fixed injection rate of 5 ml/s was used. In group B, the contrast injection rate was calculated as follows: flow rate=contrast volume/scan duration+10 s. Time to peak enhancement and peak enhancement of the main left and right pulmonary arteries were measured on single‐level, dynamic CT images for a fixed time of 30 s. Rank correlation (Spearman's) coefficients between injection duration and time to peak enhancement and between body weight and peak enhancement were calculated. For group A, there was a significant negative correlation between peak enhancement and weight (r=?0.94; P=0.005), while for group B, there was no significant correlation (r=?0.64 and P=0.18). There was a significant correlation between time to peak enhancement and injection duration in both groups (group A: r=0.99; P=0.006 and group B: r=0.85; P=0.02). In conclusion, injection duration is a key feature in a CT angiography injection protocol. A protocol with an injection duration adjusted to the scan duration seems to be particularly suitable for veterinary applications where a population with great weight variability is studied.     

Dynamic computed tomographic evaluation of the pituitary gland in healthy dogs

OBJECTIVE: To determine the contrast enhancement pattern of the pituitary gland in healthy dogs via dynamic computed tomography (CT). ANIMALS: 17 dogs. PROCEDURE: With each dog in sternal recumbency, transverse CT scans were made perpendicular to the skull base from the rostral clinoid processes to the dorsum sellae. At the position of the image that contained the largest cross section of the pituitary gland, a series of 9 to 11 scans was made during and after IV injection of contrast medium (dynamic CT scans). The contrast enhancement pattern of the pituitary gland and surrounding arteries was assessed visually and by use of time-density curves. RESULTS: After strong enhancement of the maxillary arteries, the intracavernous parts of the internal carotid arteries, and the communicating arteries of the arterial cerebral circle, there was a strong enhancement of the central part of the pituitary gland followed by enhancement of its peripheral part. On the last images of the dynamic series of the pituitary gland, the central part was hypodense, compared with the peripheral part. Time-density curves confirmed an early, strong enhancement of the central part and a delayed, less strong enhancement of the peripheral part of the gland. CONCLUSIONS AND CLINICAL RELEVANCE: The difference in enhancement between the central and peripheral parts of the pituitary gland was attributable to a difference in vascularization of the neurohypophysis and adenohypophysis, respectively. Distortion or disappearance of the strong central enhancement (pituitary flush) may be used for the detection and localization of pituitary abnormalities in the adenohypophysis.     

Effects of a hypertonic saline solution and dextran 70 combination in the treatment of diarrhoeic dehydrated calves

Thirty dehydrated diarrheic calves aged 2-45 days were used to study the effects of small volume intravenous 7.2% hypertonic saline and 6% dextran 70 solution in combination with alkalinising oral fluids and to compare this therapy with the large volume intravenous isotonic saline with alkalinising oral fluid treatment. This study included a total of 30 diarrhoeic dehydrated calves aged 2-45 days. After routine clinical and haematological examinations, the calves were allotted to two treatment groups. Isotonic saline solution (32 ml/kg, i.v.) with an oral electrolyte solution (22 ml/kg, p.o.) were administered to group I (control), and the combination of 7.2% hypertonic saline in 6% dextran 70 solutions (HSD) (4 ml/kg, i.v.) with an oral electrolyte solution (50 ml/kg, p.o.) were administered to group II (test). Additionally, an oral electrolyte solution (50 ml/kg, p.o.) was readministered to both groups at 12 h of the study. The clinical and haematological examinations of all calves were performed both before and after the treatment at the 1/2, 1, 2, 4, 12 and 24 h. The capillary refill time, peripheral pulse quality, dehydration degrees, mental status, haematocrit rates, haemoglobin and plasma values after treatment were found to be statistically different compared with the values before treatment. In comparison with group I, group II is observed to have shorter capillary refill time at 1, 4 and 12 h (P < 0.001) and better peripheral pulse quality at 1/2 (P < 0.05), 1, 2, 4 and 12 h (P < 0.001). Moreover, the degree of dehydration in group II, was significantly improved at 2 (P < 0.01), 4 and 12 h. Results of the study indicated that administration of low volumes of hypertonic sodium chloride and dextran 70 solution combinations with oral electrolyte solutions was concluded as quicker, practical, economical and most importantly an effective way for the treatment of dehydrated diarrhoeic calves.     

Therapeutic efficacy of tulathromycin, a novel triamilide antimicrobial, against bovine respiratory disease in feeder calves

Efficacy and field safety of tulathromycin administered as a single-dose treatment to crossbreed beef calves with undifferentiated bovine respiratory disease (BRD) were evaluated in a multicenter field study conducted at four US feedlots. Two hundred castrated male calves were enrolled at each study site. The treatment groups were physiologic saline (n = 160) given SC at 0.02 ml/kg, tulathromycin (n = 320) given SC at 2.5 mg/kg, and tilmicosin (n = 320) given SC at 10 mg/kg. Nasopharyngeal swabs for bacterial culture were obtained before treatment. The cure rate for calves treated with tulathromycin (78%) and tilmicosin (65%) was significantly (P < or = .0001) higher than that of calves treated with saline (23.8%). The cure rate of calves treated with tulathromycin (78.4%) was significantly (P = .0007) higher than that of calves treated with tilmicosin (64.9%). No adverse events related to tulathromycin were reported. Under the conditions of this study, tulathromycin administered as a single-dose treatment was efficacious in the treatment of undifferentiated BRD.     

Serum activity/concentration profiles of a sustained-released formulation of sulphathiazole-trimethoprim (2.5:1) in calves

Thirty-six two-week-old healthy Holstein-Friesian calves weighing between 52 and 58 kg were divided at random into three groups of 12; group A calves were given a single oral bolus containing 2.5 g sulphathiazole and 1 g trimethoprim in a sustained-release formulation; group B received the same doses of the drugs but the trimethoprim was not in a sustained-release formulation; group C received a bolus containing 2.5 g sulphathiazole and 0.5 g conventional trimethoprim. Blood samples were collected at intervals for two days, the serum was separated and the composite antibacterial activity profiles of the mixture were analysed by an agar-diffusion microbiological method. The mean maximum activities in the serum of the three groups were 23.4 microg/ml in group A, 9.25 microg/ml in group B and 8.01 microg/ml in group C. The mean areas under the curves of the serum activity time curves were 838 microg/ml/hour in group A, 216 microg/ml/hour in group B and 182 microg/ml/hour in group C.     

DYNAMIC COMPUTED TOMOGRAPHY OF THE NORMAL FELINE HYPOPHYSIS CEREBRI (GLANDULA PITUITARIA)

The purpose of this study was to describe normal feline hypophyseal mensuration and contrast enhancement characteristics using dynamic computed tomography (CT) imaging. An intravenous bolus of an ionic iodinated contrast medium was administered to eight cats using a pressure injector while dynamic CT images were obtained every 5 s for five cats and every 7 s for three cats for a total imaging time of 5 min. Each pituitary was measured at its maximum height and width on the peak contrast medium enhancement image. A hand-drawn region of interest was placed around each hypophysis cerebri and time attenuation curves were generated. The specific enhancement pattern of the hypophysis cerebri for each cat was recorded. The mean width and height of the hypophysis cerebri was 5.2 +/- 0.4 (average +/- SD) mm and 3.1 +/- 0.3 mm, respectively. The mean time to maximum contrast enhancement was 28.6 +/- 14.8 s (range 14-50 s) from the onset of contrast medium injection. Four cats had initial dorsal and peripheral contrast enhancement patterns of the hypophysis cerebri, while four cats had an initial central contrast medium enhancement pattern. The hypophysis cerebri had a homogenous appearance in all cats, 28-50 s after contrast medium injection. The average (+/- SD) clearance half-time was 292 (+/- 87) s. Normal hypophysis cerebri mensuration and contrast medium enhancement characteristics will help in clinical evaluation of the feline hypophysis cerebri.     

Persistent efficacy of doramectin injectable against artificially induced infections with Cooperia punctata and Dictyocaulus viviparus in cattle.

Three studies were conducted to evaluate the persistent efficacy of doramectin injectable solution against experimental challenges with infective larvae of Cooperia punctata and Dictyocaulus viviparus. In each study, four groups of ten randomly-assigned calves, negative for trichostrongyle-type eggs on fecal examination, were treated subcutaneously in the midline of the neck with saline (1 ml/50 kg) on Day 0 or doramectin (200 microg/kg = 1 ml/50 kg) on Day 0, 7, or 14. Two additional calves from the same pool of animals were randomly assigned as larval-viability monitors and received no treatment. On Days 14-28, approximately 1000 and 50 infective larvae of Cooperia spp. and D. viviparus, respectively, were administered daily by gavage to each animal in Groups T1-T4. On Day 28, the two larval-viability monitor calves were inoculated in a similar manner with a single dose of approximately 30000 and 2000 larvae of Cooperia spp. and D. viviparus, respectively. Equal numbers of calves from each treatment group were killed on Days 42-45, as well as the two viability monitor animals to enumerate worm numbers. A 2% or 5% aliquot of small intestinal contents and washings were examined for worm quantification and identification, while 100% of the lung recoveries were quantified and identified. For each study and across the three studies, geometric mean worm recoveries for each treatment group were calculated from the natural log transformed data (worm count + 1) and were used to estimate percentage reduction. In the three studies, doramectin injectable solution was 97.5% efficacious against lungworms for up to 28 days and was 99.8% efficacious in reducing infection resulting from challenge with infective larvae of C. punctata for at least 28 days post-treatment.     

Clinical effectiveness of tulathromycin, a novel triamilide antimicrobial, for the control of respiratory disease in cattle at high risk for developing bovine respiratory disease

The efficacy of tulathromycin in decreasing the incidence of morbidity and mortality due to bovine respiratory disease (BRD) in 1,239 high-risk cattle was investigated at four US feedlots. Calves not exhibiting clinical signs of BRD received one of three treatments administered subcutaneously in the neck: physiologic saline at 0.02 ml/kg, tulathromycin at 2.5 mg/kg, or tilmicosin at 10 mg/kg. Each treatment group consisted of 413 calves. Calves with clinical signs of BRD and rectal temperatures of 104 degrees F or higher on days 1 through 14 were considered treatment failures (BRD morbidity). Nasopharyngeal swabs from saline-treated morbidities were submitted for isolation and identification of BRD organisms. Respiratory disease morbidity was highest in calves treated with saline and significantly (P < or = .0001) lower in calves administered tulathromycin or tilmicosin. Morbidity from BRD was significantly (P < or = .0001) higher in calves treated with tilmicosin than in calves treated with tulathromycin. Under conditions of this study, tulathromycin, given to calves at high risk of developing BRD, was significantly more effective in reducing BRD morbidity when compared to both saline- and tilmicosin-treated calves.     

The effect of treatment with eprinomectin on lungworms at early patency on the development of immunity in young cattle

An experiment was carried out to study the effect of topical application of eprinomectin at early patency on the build up of infection and development of protection against Dictyocaulus viviparus in young cattle. Three groups of six calves were used and parasitological and blood variables were monitored at weekly intervals throughout the trial. At the start of the experiment calves in groups A and B were experimentally inoculated with 100 D. viviparus infective third-stage larvae (L3) for five consecutive days, whereas calves in group C served as uninfected controls. The calves in group A were each treated with eprinomectin (0.5mg/kg bodyweight) in a pour-on formulation at early patency at day 24 post the first inoculation, whereas the calves in groups B and C were left untreated. Seven weeks following anthelmintic treatment all groups were challenged with 1500 L3. Another 4 weeks later the animals were sacrificed and established worms in the lungs were counted. Moderate transient signs of lungworm disease occurred both in groups A and B. However, group B calves were found to be about 8 times more resistant than those in group A, whereas the naive infection controls in Group C was found to be about 35 times more susceptible to infection. Also the ELISA values showed that the course of infection was different between experimental groups. The eosinophil counts prior to and at the time of slaughter indicate that immunity was involved in the protection and the response was correlated with previous exposure and worm load. Weight gains differed significantly, but only between groups A and C and between groups B and C that on an average were approximately 13kg heavier at the termination of the experiment. It was concluded that eprinomectin was effective against established adult lungworms. However, the untreated calves (group B) developed a more marked resistance to lungworms compared to those that were subjected to anthelmintic treatment at early patency (group A). On the other hand, the cumulative number of excreted larvae was on an average 43 times higher in group B as compared to group A. Consequently, infected calves that remain out on pasture should be treated. This will restrain transmission of the parasite despite the fact that immunity is deteriorated.     

Effects of Nigella sativa L. and Urtica dioica L. on lipid peroxidation, antioxidant enzyme systems and some liver enzymes in CCl4-treated rats

This study was designed to investigate the effects Nigella sativa L. (NS) and Urtica dioica L. (UD) on lipid peroxidation, antioxidant enzyme systems and some liver enzymes in carbon tetrachloride (CCl4)-treated rats. A total of 60 healthy male Sprague-Dawley rats were utilized in this study. The rats were randomly allotted into one of four experimental groups: A (CCl4-only treated), B (CCl4 + UD treated), C (CCl4 + NS treated) and D (CCl4 + UD + NS treated), each containing 15 animals. All groups received CCl4 [0.8 ml/kg of body weight, subcutaneously, twice a week for 90 days starting day 1]. In addition, B, C and D groups also received daily intraperitoneal injections of 0.2 ml/kg NS or/and 2 ml/kg UD oils for 45 days starting day 46. Group A, on the other hand, received only 2 ml/kg normal saline solution for 45 days starting day 46. Blood samples for the biochemical analysis were taken by cardiac puncture from five randomly chosen rats in each treatment group at beginning, at 45th and at 90th day of the experiment. The CCl4 treatment for 45 days increased the lipid peroxidation and liver enzymes, and also decreased the antioxidant enzyme levels. NS or UD treatments (alone or combination) for 45 days starting day 46 decreased the elevated lipid peroxidation and liver enzyme levels and also increased the reduced antioxidant enzyme levels. Live weights of the rats decreased in group A, and increased in groups B, C and D. It is concluded that NS and UD decrease the lipid peroxidation and liver enzymes, and increase the antioxidant defence system activity in the CCl4-treated rats.     

THE COMPUTED TOMOGRAPHIC ENHANCEMENT PATTERN OF THE NORMAL CANINE PITUITARY GLAND

Dynamic computed tomography (CT) of the pituitary gland was performed on four healthy male dogs of similar size, weight and age. The pituitary gland region was first identified on lateral scout and transverse non-contrast images. After localization, water soluble iodinated contrast medium was administered intravenously as a bolus at a dose of 1 ml/lb using a pressure injector at an injection rate of 10 ml/sec and a total of 40 post contrast images of the pitutary gland were acquired. No images were made after 400 seconds. The same pituitary region was imaged in each slice. The slice thickness was 1.5 mm, with a two second scan time and an eight second delay between images (resulting in images every ten seconds). The contrast medium injection and initial image were acquired simultaneously, resulting in a non-contrast enhanced initial image. At the completion of the CT scan, a region of interest (ROI) was drawn around the pituitary gland and time density data were obtained. The mean pituitary Hounsfield number was plotted as a function of time. A bi-exponential least squares model was used to derive the best fitting line through the data. The mean relative peak increase in pituitary Hounsfield Units (HU) was 65.9% +/- 2.1%. After the initial increase there was a decrease in pituitary Hounsfield number with a half-time of 16.1 seconds, followed by a slower phase with a half-time of 16.5 minutes. The mean pituitary gland HU value during the period of gradual opacity decline was 35.0% +/- 4.4% above that of the pre-contrast image. Establishing the enhancement pattern in the canine pituitary gland is the precursor to the clinical application of dynamic CT of the pituitary gland to diagnose pituitary microadenomas and/or small macroadenomas before they become exceptionally large.     

Immunologic response and resistance to experimentally induced pneumonic pasteurellosis in cattle vaccinated with various dosages of lyophilized Pasteurella haemolytica

Pasteurella haemolytica was lyophilized in an enriched soybean polypeptone broth. Lyophilization in this medium resulted in a mean 10-fold loss in P haemolytica viability, as opposed to up to a 10(4)-fold loss in viability when other media were used. Lyophilized P haemolytica was reconstituted and used as a live vaccine in 3 experiments. Calves were challenge exposed by transthoracic injection with virulent P haemolytica. In experiment 1, 2 subcutaneous injections (7-day interval between injections) with 5 ml of recently harvested (1 X 10(9) colony-forming units [CFU]/ml) or lyophilized (1 X 10(8) CFU/ml) P haemolytica significantly (P less than 0.001) enhanced resistance against challenge exposure, compared with resistance in calves given saline solution or sterile medium (control calves) or calves vaccinated with lyophilized organisms at a concentration of 1 X 10(6) CFU/ml. In experiment two, 1, 2, or 5 ml of lyophilized P haemolytica (1 X 10(8) CFU/ml) significantly (P less than 0.05) enhanced resistance, compared with resistance in calves given saline solution (control calves). In experiment three, 1 or 2 injections of lyophilized P haemolytica significantly (P less than 0.01) enhanced resistance against challenge exposure, compared with that of calves given saline solution. The mean lesion score for calves given 1 injection was not significantly higher than the mean lesion score for the group given 2 injections. Vaccination with lyophilized P haemolytica vaccine caused significant (P less than 0.05) increases in serum antibody to P haemolytica somatic antigens, to a carbohydrate-protein subunit of the organism, and to leukotoxin.     

Computed tomographic densitometry of normal feline thyroid glands

We studied the computed tomographic (CT) appearance and determined Hounsfield units (HU) for normal thyroid tissue in eight cats. Helical CT images (2 mm collimation) were acquired from cranial aspect of the second cervical vertebra (C2) through caudal aspect of the fourth cervical vertebra (C4). Data were acquired before contrast medium administration (n = 7), after delayed contrast medium enhancement (n = 8), and immediately after contrast medium enhancement after a second dose of contrast medium (n = 8). Attenuation of thyroid tissue was compared with surrounding tissues. Before contrast medium enhancement, thyroid tissue was hyperattenuating to the surrounding soft tissues. After delayed contrast medium enhancement, thyroid tissue was hyperattenuating to surrounding soft tissues and isoattenuating to contrast medium-laden blood vessels. Immediately after contrast medium enhancement, thyroid tissue was hyperattenuating to surrounding soft tissues and hypoattenuating to contrast medium-laden blood vessels. The thyroid glands were dorsolateral to the trachea, ovoid, and displayed homogenous contrast medium enhancement. Circular regions of interest were drawn on the right and left thyroid lobes. Densitometric data of thyroid tissue were as follows: precontrast medium enhancement, 123.2 HU (95% CI: 119.4-127.1 HU); delayed contrast medium enhancement, 132.1 HU (95% CI: 127.4-136.8 HU); immediate postcontrast medium enhancement, 168.5 HU (95% CI: 163-173.9 HU). Normal feline thyroid tissue is easily detected using CT without contrast medium enhancement. This information may be useful for CT evaluation of abnormal feline thyroid glands.     

Chemoimmunoprophylaxis against bovine tropical theileriosis in young calves: a comparison between buparvaquone and long-acting oxytetracycline

Eighteen seven to 21-day-old crossbred (Bos taurus cross Bos indicus) calves were allocated to four groups (A to D). Groups A and B each consisted of six calves and groups C and D three calves each. Each calf in groups A, B and C was inoculated with ground-up tick supernate (GUTS) equivalent to two infected acini prepared from Theileria annulata-infected Hyalomma anatolicum anatolicum. Each calf in group A was also given a single intramuscular injection of buparvaquone, 2.5 mg kg-1 bodyweight simultaneously with GUTS, whereas each calf in group B was given a single intramuscular injection of long-acting oxytetracycline, 20 mg kg-1 bodyweight following inoculation of GUTS. In calves of group A clinicopathological reactions were negligible, whereas in calves of group B mild to severe reactions were observed resulting in the death of three of the six calves. All the calves of group C (infected, untreated controls) died of acute theileriosis. All the surviving calves of groups A and B withstood a lethal homologous challenge given on day 30 after immunisation, indicating no difference in the immune status of the surviving calves of the two groups. Group D, challenge control, all calves died of theileriosis within 18 days of challenge.     

HELICAL COMPUTED TOMOGRAPHIC ANGIOGRAPHY OF THE NORMAL CANINE PANCREAS

Helical abdominal computed tomography (CT) was performed in nine normal beagle-mix dogs. Following cephalic vein injection of ionic iodinated contrast medium via power injector (rate 5 ml/s) dual-phase CT was performed in all dogs. A delayed scan was performed in five dogs between 5 and 13 min after the contrast medium injection. The median time of appearance of contrast medium in the aorta and gastroduodenal artery was 6.3 and 7 s, post start injection and 12 and 12.2 s in the gastroduodenal and portal vein, resulting in a purely arterial pancreatic time window of 5-6s. Pancreatic veins and parenchyma remained enhanced until the end of the dynamic scan (40s). The pancreatic parenchyma showed heterogeneous arterial and homogenous venous contrast enhancement which was slightly hypoattenuating compared to the liver. Delayed scans provided best delineation of the pancreas from the liver. The common bile duct could be identified ventral and to the right of the portal vein joining the dorsomedial aspect of proximal duodenum. Because of the very short time window and variable onset of pure arterial enhancement careful planning of dual-phase studies with previous dynamic CT is recommended. Dual-phase CT angiography enables assessment of the arterial supply, parenchymal perfusion and venous drainage of the canine pancreas.